The present invention relates to a portable drill which can be mounted to a work surface, and more particularly to a quill feed for a magnetic based drill or other drill having a base that can be attached to a work surface.
Magnetic based drill assemblies (magdrills) are used extensively in the metal fabricating field for forming holes in various workpieces where it is either impractical or inconvenient to move the workpiece to a conventional drill press. Accordingly, as the magdrill is moved to the workpiece, it is advantageous to provide the most portable and compact drill assembly possible. Additionally, as the drill assembly is operated in a construction environment it is preferable that the magdrill have a minimum number of exposed moving parts. The minimization of exposed parts improves the durability and the maintenance requirements of the magdrill.
Typically, magnetic based drill assemblies have an arbor coupled to a motor which is attached to a slide assembly. The slide assembly is mounted for vertical movement in relation to a magnetic base. A handle is typically used to rotate a gear which rectilinearly moves the slide assembly between a retracted position and an extended position to form a hole in a workpiece. Thus, to drill a hole, the entire motor, arbor, slide, and drill tool must be slidably actuated in a vertical plane relative to the magnetic base.
Drilling a precision hole in a substantial workpiece such as a steel I-beam, pipe or plate, requires a relatively powerful electrical motor to maintain an acceptable rate of operation. Due to the strength and precision required to moveably support the entire motor, arbor, slide, and drill tool, the drill assembly is relatively bulky and difficult to maneuver along a workpiece. Additionally, the quantity, weight and height of the moving parts provide an unbalanced drill assembly having a center of gravity which changes as the moving parts are vertically manipulated during drilling operations. The multiple moving parts, bulkiness, and unbalanced nature of conventional magdrill assemblies thus increase the amount of maintenance required to keep the drill assembly operational.
Further, it is preferable to introduce a liquid coolant to the drill tool and workpiece during operation of the drill assembly to reduce friction and heat. The liquid coolant is commonly provided from a storage tank to the drill tool by gravity or pressure. To introduce coolant to a drill tool through typical arbors commonly requires a series of intricately formed passageways or the installation of an adaptor adjacent the drill tool. However, in addition to the complexity of either method, the coolant is not fed directly into the drill tool which thereby reduces coolant and drill tool effectiveness.
Thus, there is a need for a magnetic based drill which is compact, has a minimum number of exposed moving parts and is of a relatively light weight.